Thursday, March 25, 2021

Re: Double equals

In GWT Boolean, Double and String are represented using their unboxed primitive types.

See for Double:

So when compiled to JavaScript Double.equals() would be called with primitive types and that's why it can generally do an instance equality check. However Double.NaN is represented using JavaScript NaN (see: ) and in JavaScript NaN == NaN is always false. 

So I would consider it an emulation bug and equals() needs to check for NaN and handle it correctly with regard to Java behavior. Feel free to create a bug for it on GitHub.

-- J. schrieb am Donnerstag, 25. März 2021 um 09:38:28 UTC+1:
Can someone help me with the double.equals
with the following simple code:
      Double value1 = Double.NaN;
      Double value2 = Double.NaN;

      boolean result1 = value1.equals(value2);

In Java result1 = true;
In web with GWt result1 = false;

Looking at the sourcecode i see that the java double has the following equals method:
public boolean equals(Object obj) { 
return (obj instanceof Double) && (doubleToLongBits(((Double)obj).value) == doubleToLongBits(value));

the GWT double source code shows the following:
public boolean equals(Object o) {
return checkNotNull(this) == o;

I do not really understand the GWT version. th emost important thing is that the equals has different results between java and GWT.
How to resolve this?



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